I'm trying to switch from squatting high-bar to more of a low-bar position for two reasons. First, the high-bar squat seems to be mechanically difficult for me and I'm able to maintain much better technique, keep the stress off of my wonky knees and (logically) lift more using a low-bar position. Second, I've been experiencing light elbow tendonitis of late (golfer's elbow) and can pretty much chalk it up to having to support a lot of the bar's weight using my hands (and, ultimately, wrists and elbows) while high-bar squatting.
There is one big problem in my transition to low-bar: it kills my shoulders, and I'm sure that this is a mobility issue. I have pretty bad thoracic/overhead mobility and I can't really get into a comfortable position while staying tight in the upper back. I've been following Rippetoe's advice on hand and bar placement for the low-bar squat (as per the following YouTube video), since this takes almost all of the pressure off of the elbows. However, I can't reasonably hold this position for more than a couple of reps, since my shoulders begin to burn.
Has anyone had a similar problem? I've been working on my overall thoracic mobility with the foam roller and using various drills, but does anyone have any warm-up tips for squat workouts that would loosen up the shoulders, or any pointers for the set-up that might alleviate this problem?
Thanks in advance!